Chapter 25: Cancer survival in Chiang Mai, Thailand, 1993-1997
Sumitsawan Y, Srisukho S, Sastraruji A, Chaisaengkhum U, Maneesai P and Waisri N
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The registry contributed data on survival from 37 cancer sites or types for the first volume of the IARC publication on Cancer Survival in Developing Countries[2]. Data on survival from 36 cancer sites or types registered during 1993–1997 are reported in this second volume.
The closing date of follow-up was 31st December 2000. The median follow-up ranged between 1.4 months for unspecified leukaemia to 39 months for breast and corpus uteri cancers. Complete follow-up information at five years from the incidence date ranged from 100% for unspecified leukaemia to 59% for non-melanoma skin cancer. The proportion of cases lost to follow-up was generally the highest within 3 years from the incidence date.
The 5-year age-standardized relative survival (ASRS) probability for all ages together was generally less than or similar to the corresponding unadjusted one for most cancers. Also, the 5-year ASRS (0–74 years of age) was generally higher than or similar to the corresponding ASRS (all ages) for a majority of cancers.
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Abstract
The Chiang Mai tumour registry was established in 1978 as a hospital-based cancer registry, and population-based cancer registration started in 1986, with retrospective data collection on cancer incidence and mortality since 1983. Registration of cases is done by active method. Data on survival for 36 cancer sites or types registered during 1993–97 are reported here. Follow-up has been carried out predominantly by active methods, with median follow-up ranging between 1–39 months for different cancers. The proportion of histologically verified diagnosis for various cancers ranged between 28–100%; death certificate only (DCOs) cases comprised 0–56%; 33–92% of total registered cases were included for survival analysis. Complete follow-up at five years ranged from 59–100% for different cancers. The 5-year age-standardized relative survival rates was the highest for Hodgkin lymphoma (70%) followed by thyroid (65%), cervix (57%), breast (56%) and corpus uteri (49%). The 5-year relative survival by age group showed either an inverse relationship or was fluctuating. An overwhelmingly high proportion of cases were diagnosed with a regional spread of disease, ranging between 44–82% for different cancers and survival decreased with increasing extent of disease for all cancers studied.ChiangMai tumour registry
The Chiang Mai tumour registry was established in 1978 as a hospital cancer registry in The Maharaj Nakorn Chiang Mai Hospital and is finaly supported by the Faculty of Medicine, Chiang Mai University. Population-based cancer registration started in 1986, with retrospective data collection on cancer incidence and mortality since 1983. The registry has been contributing data to the quinquennial IARC publication Cancer Incidence in Five Continents since Vol VI[1]. Cancer registration is done by active methods. The principal sources of information on cancer cases are the hospital and pathology records. The registry caters to a mixed urban and rural population of about 1.4 million with a sex ratio of 995 females to 1000 males in 1995. The average annual age-standardized incidence rate is 145 per 100 000 among males and 151 per 100 000 among females with a lifetime cumulative risk of one in 6 of developing cancer for both sexes in the period 1993–1997. The top-ranking cancers among males are lung followed by liver and stomach. Among females, the order is cervix, lung and breast.Map. Map showing location of Chiang Mai, Thailand Click here to open map (PDF format) |
Data quality indices
The proportion of cases with histologically verified cancer diagnosis in our series is 77%, varying between 28–100%. The proportion of cases registered as death certificate only (DCOs) is 5.5%, ranging between nil for many cancers and 56% for unspecified cancer. Cases excluded without any follow-up constitute 16%. The exclusion of cases from the survival analysis is the greatest among the gastrointestinal cancer of the gallbladder (67%) and the least among lymphoid leukaemia (8%). Thus, 33–92% of the total cases registered are included in the estimation of the survival probability.Table 1. Data quality indices - Proportion (%) of histologically verified and death certificate only cases, number and proportion of included and excluded cases by site, Chiang Mai, Thailand, 1993–1997 cases followed-up until 2000 Click here to open table (PDF format) Click here to open comparative statistics by registry |
Outcome of follow-up
Follow-up has been carried out predominantly by active methods. These included abstraction of cancer mortality information from the Chiang Mai public health service records. The abstracted data are matched with the incident cancer database. Unmatched incident cases are then subjected to one or more of the following to obtain the vital status information: repeated scrutiny of records in the respective sources of registration, postal enquiry and house visits.The closing date of follow-up was 31st December 2000. The median follow-up ranged between 1.4 months for unspecified leukaemia to 39 months for breast and corpus uteri cancers. Complete follow-up information at five years from the incidence date ranged from 100% for unspecified leukaemia to 59% for non-melanoma skin cancer. The proportion of cases lost to follow-up was generally the highest within 3 years from the incidence date.
Table 2. Number and proportion of cases with complete / incomplete follow-up and median follow-up by site, Chiang Mai, Thailand, 1993–1997 cases followed-up until 2000 Click here to open table (PDF format) Click here to open comparative statistics by registry |
Survival statistics
All ages and both sexes together
The 5-year relative survival is the highest for corpus uteri cancer (68%) followed by thyroid (67%), breast (62%), cervix (60%) and Hodgkin lymphoma (53%). The lowest survival rate is encountered with liver cancer, with a figure of 3%. Nasopharynx (37%), among other head and neck cancers, and colon (31%), among gastrointestinal cancers, have the highest survival. Survival from cancers of the urinary system is 31% for urinary bladder and 19% for kidney. Hodgkin lymphoma had a better survival (53%) than non-Hodgkin (26%). The survival figures for leukaemias are 20% for lymphoid, 11% for myeloid and 10% for unspecified.The 5-year age-standardized relative survival (ASRS) probability for all ages together was generally less than or similar to the corresponding unadjusted one for most cancers. Also, the 5-year ASRS (0–74 years of age) was generally higher than or similar to the corresponding ASRS (all ages) for a majority of cancers.
Table 3. Comparison of 1-, 3- and 5-year absolute and relative survival and 5-year age-standardized relative survival (ASRS) by site, Chiang Mai, Thailand, 1993–1997 cases followed-up until 2000 Click here to open table (PDF format) Click here to open comparative statistics by registry | |
Figure 1a. Top ten cancers (ranked on survival), Chiang Mai, 1993–1997 Click here to open figure (PDF format) Click here to open graph for all the cancer sites |
Sex
Table 4a. Site-wise number of cases, 5-year absolute and relative survival by sex, Chiang Mai, Thailand, 1993–1997 cases followed-up until 2000 Click here to open table (PDF format) Click here to open comparative statistics by registry |
Male
The top five cancers ranked on the 5-year relative survival were Hodgkin disease (59%), thyroid (49%), soft tissue (47%), non-melanoma skin (39%) and prostate (35%). Survival from Hodgkin lymphoma and laryngeal cancer was noticeably higher among males than females.Figure 1b. Top five cancers (ranked on survival), Male, Chiang Mai, 1993–1997 Click here to open figure (PDF format) Click here to open graph for all the cancer sites |
Female
The top-ranking cancers in terms of 5-year relative survival are thyroid (73%), corpus uteri (68%), breast (62%), cervix (60%) and non-melanoma skin (52%). Survival was distinctly higher among females than males for cancers of the oral cavity, nasopharynx, oesophagus, gallbladder, bone, non-melanoma skin and brain, thyroid and non-Hodgkin lymphoma and unspecified leukaemia.Figure 1c. Top five cancers (ranked on survival), Female, Chiang Mai, 1993–1997 Click here to open figure (PDF format) Click here to open graph for all the cancer sites |
Age group
The 5-year relative survival by age group reveals an inverse relationship: a decreasing survival with increasing age at diagnosis for cancers of the cervix and body uterus. In the rest, it is observed to be fluctuating.Table 4b. Site-wise number of cases, 5-year absolute and relative survival by age group, Chiang Mai, Thailand, 1993–1997 cases followed-up until 2000 Click here to open table (PDF format) Click here to open comparative statistics by registry |
Extent of disease
An overwhelmingly high proportion of cases among the few selected cancers with reliable information on extent of disease are diagnosed, with a regional spread of disease ranging from 82% for larynx cancer to 44% for ovarian cancer. There is not much of a difference in the frequency of cases with a localized disease (14%) and a distant metastasis (12%) in breast cancer. Less than 4% of cases presented with localized disease among colorectal cancers. The extent of disease was unknown in 0–4%. The 5-year absolute survival by extent of disease followed the expected pattern: highest for localized cases followed by regional and distant metastasis cases among known categories of extent of disease.Table 5. Proportion (%) of cases and 5-year absolute survival by extent of disease and site, Chiang Mai, Thailand, 1993–1997 Click here to open table (PDF format) Click here to open comparative statistics by registry | |
Figure 2a-2f. Absolute survival from selected cancers by extent of disease: Chiang Mai, Thailand open figures in PDF format | |
Figure 2a. Absolute survival by extent of disease: Chiang Mai, Thailand: Cancer of the colon Click here to open figure (PDF format) Click here to open comparative statistics by cancer site | |
Figure 2b. Absolute survival by extent of disease: Chiang Mai, Thailand: Cancer of the rectum Click here to open figure (PDF format) Click here to open comparative statistics by cancer site | |
Figure 2c. Absolute survival by extent of disease: Chiang Mai, Thailand: Cancer of the larynx Click here to open figure (PDF format) Click here to open comparative statistics by cancer site | |
Figure 2d. Absolute survival by extent of disease: Chiang Mai, Thailand: Cancer of the breast Click here to open figure (PDF format) Click here to open comparative statistics by cancer site | |
Figure 2e. Absolute survival by extent of disease: Chiang Mai, Thailand: Cancer of the cervix Click here to open figure (PDF format) Click here to open comparative statistics by cancer site | |
Figure 2f. Absolute survival by extent of disease: Chiang Mai, Thailand: Cancer of the ovary Click here to open figure (PDF format) Click here to open comparative statistics by cancer site |
Survival trend
The 5-year relative survival for cases registered in 1993–1997 compared to those in 1983–1992[2] shows a marked decrease in cancers of the tongue, bone, skin melanoma, non-melanoma skin, vulva and penis. There has been an increase in survival in the corresponding period for cancers of the connective tissue, thyroid and Hodgkin lymphoma. For the rest, the absolute difference in survival is <10%. The level of complete follow-up in this volume has decreased in 25 out of 33 cancers compared to previous volume.Table 6. Comparison of 5-year absolute and relative survival of cases diagnosed between 1985–1992 and 1993–1997, Chiang Mai, Thailand Click here to open table (PDF format) Click here to open comparative statistics by registry |
References
- Parkin DM, Whelan SL, Ferlay J and Storm H. Cancer Incidence in Five Continents, Vol I to VIII: IARC Cancerbase No. 7. IARCPress, Lyon, 2005.
(link to CI5) - Martin N, Srisukho S, Kunpradist O and Suttajit M. Cancer survival in Chiang Mai, Thailand. In: Cancer Survival in Developing Countries (eds) R Sankaranarayanan, RJ Black and DM Parkin. International Agency for Research on Cancer, IARC Scientific Publications No. 145. IARCPress, Lyon, 1998.
(link to Cancer Survival, volume 1)